Oxygen and nitrogen Lewis base adducts of [UO2(OTf)2]. Crystal structures of polypyridine complexes with out-of-plane uranyl equatorial coordination
2004; Royal Society of Chemistry; Issue: 17 Linguagem: Inglês
10.1039/b405287k
ISSN1477-9234
AutoresJ.‐C. Berthet, M. Nierlich, M. Ephritikhine,
Tópico(s)Chemical Synthesis and Characterization
ResumoDissolution of [UO2(OTf)2] (1) in anhydrous thf, dme or py led to the formation of the complexes [UO2(OTf)2(thf)3] (2), [UO2(OTf)2(dme)] (3) and [UO2(OTf)2(py)3] (4), respectively. Compounds 2 and 4 are neutral monomers in the solid state as well as the chloride [UO2Cl2(py)3] (5) which was prepared in a similar way as for 4 from the dimer [{UO2Cl2(thf)2}2]. Addition of 4 equivalents of triphenylphosphine oxide (tppo) to 1 afforded, in pyridine, the dicationic species [UO2(tppo)4][OTf]2 (6). The bi- or terdentate nitrogen molecules 2,2′-bipy, phen or terpy reacted with 1 in acetonitrile or pyridine to give [UO2(OTf)2(bipy)2] (7), [UO2(phen)3][OTf]2 (8), [UO2(OTf)2(terpy)] (9) and [UO2(terpy)2][OTf]2 (10), respectively. The hydroxide compound [{UO2(OH)(terpy)}2][OTf]2 (11) was obtained by hydrolysis in air of 1 in a mixture of acetonitrile and ethanol in the presence of terpyridine. The X-ray crystal structures of 7, 8 and 10 reveal a novel coordination geometry for the uranyl ion, the uranium atom being in a rhombohedral environment; the six coordinating ligands atoms of the {UO2}2+ ion are separated into two parallel and staggered equilateral triangles and the UO2 axis is perpendicular to these triangles, passing through their centre. The structures of the mono(terpy) complexes 9 and 11 show the uranium atoms in a distorted pentagonal bipyramidal configuration with the nitrogen atom of the central pyridine ring of the terpy ligand significantly displaced from the equatorial plane.
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